海洋环境因素极值组合及设计标准

Combination of Sea Environmental Events and Design Criteria

由于海洋环境条件的复杂性、多变性及随机性，设计标准的选取是决定工程结构安全度、造价、效益及合理型式的主要因素。传统的设计标准，无法考虑海洋环境条件的随机组合，往往过高估计环境条件设计标准，造成不必要的浪费，甚至使具有开发前景的油田失去开采价值。以实测和后报资料为基础，使用多维联合概率的随机模拟技术，结合不同结构型式的极值响应及不同资料样本的选择方法，提出了海洋工程结构物上的风、浪、流、潮联合荷载及相应的联合概率水平问题，用以作为海洋工程环境荷载设计标准。

Extreme sea statistics and combinations of environmental events or response for structures are very important problem in performance evaluation and design of coastal and offshore structures. A probabilistic method is developed that leads to the combination of typhoon (hurricane) or winter storm induces winds, waves, currents and surge for a generic site. The traditional recommendation for the fixed structures is a combination of the 100 years maximum wave height with the 100 years wind and current. This approach is, however, unduly conservative, since the largest wind, wave and current values in 100 years are not expected to occur at precisely the same time. Previous studies of combinations of extreme sea environmental conditions fall into two categories: first, the generic load model defines a surface in the multivariate space of meteorologicaloceanic variables, such as the joint probability of waves, currents, winds and storm surges; second, use of the structural response to combine the environmental variables, such as overturning moment (OTM), base shear forces and etc. While the great majority of publications are concentrated in combinations of responses, although 100 years response is not corresponding to wave,wind and current with 100 years joint probability. Since the combination design criteria is considered with extreme statistics of individual environmental events and their joint probability, in this paper some new concept for mentioned above problems is proposed.